1. Technical Field
The present invention relates to a physical quantity sensor element, a physical quantity sensor, electronic equipment, and a movable body.
2. Related Art
Recently, as a physical quantity sensor element using a silicon micro electro mechanical system (MEMS) technology, for example, a capacitance type gyro sensor element (an angular velocity sensor) for detecting angular velocity has been known (for example, refer to JP-A-2000-337884).
For example, an angular velocity sensor according to JP-A-2000-337884 is provided with a support fixing portion, a first vibrating body (a driving portion) which is supported with respect to the support fixing portion via a first supporting beam, and a second vibrating body (a detecting portion) which is supported with respect to the first vibrating body via a second supporting beam. In the angular velocity sensor, a load vibrating body including the first vibrating body and the second vibrating body vibrates in an X-axis direction (driving vibration). At the time of the driving vibration, in accordance with the action of the angular velocity about a Z-axis which passes through the center of the load vibrating body, the load vibrating body rotates and vibrates (detecting vibration) also in a Y-axis direction by Coriolis effect. In accordance with the detecting vibration, an electrostatic capacity between an interdigital electrode which is provided in the second vibrating body and a fixedly disposed interdigital electrode is changed, and a rotation angular velocity is obtained based on the electrostatic capacity.
However, in the angular velocity sensor according to JP-A-2000-337884, the second vibrating body for detecting vibration is supported by the first vibrating body for driving vibration via the second supporting beam, and thus when unnecessary vibration is generated in a direction different from a desired driving vibration, the unnecessary vibration is transferred to the second vibrating body from the first vibrating body via the second supporting beam, thereby causing deterioration of detection accuracy. For example, a cross-sectional shape of the first supporting beam is supposed to be, for example, a rectangular shape which is an ideal shape; however, the cross-sectional shape may become a parallelogram shape or a trapezoid shape without being the ideal shape due to a processing error in some cases. In this case, when the driving vibration is performed on the first vibrating body in the X-axis direction, due to the influence of the cross-sectional shape of the first supporting beam, the vibration of the first vibrating body includes not only a vibration component in the X-axis direction which is a direction of a desired driving vibration, but also a vibration component corresponding to the unnecessary vibration in the Z-axis direction. At this time, this unnecessary vibration is transferred to the second vibrating body as well, and thus leakage vibration occurs, thereby causing the detection accuracy to be deteriorated.